A lateral blocking arm which is mounted to an upright post and forms a parking space barrier is described in U.S. Pat. No. 3,913,264. U.S. Pat. No. 3,295,556 discloses a bendable tubular conduit which may be folded or bent without the walls thereof being permanently deformed. U.S. Pat. No. 4,201,830 discloses an energy absorbing structure having a rod-like lateral cross section in which an inner structural member is made of a material capable of providing rigid structural strength, but being frangible upon sharp impact, and an exterior covering generally surrounding the inner member which, in the event that the inner member breaks, prevents sharp ends of edges of the broken inner member from protruding, and impaling an individual who impacts the structure. Among the suitable material for the structure, structural foam polycarbonate is mentioned for the inner member and polyvinyl chloride is mentioned as the exterior covering. U.S. Pat. No. 4,364,200 discloses a gate apparatus comprising a member which is an elongate tube of plastic material and is movable angularly upward in a disclosed manner. Australian Pat. No. 255,338 discloses a surveyor's pole which is encased throughout its length with plastic tubing or sheathing in standard survey colors. French Pat. No. 1,044,247 and 1,400,069 both disclose covering of wood core or equivalent by a protective sheath, including a plastic sheath.
The invention will be further illustrated by reference to the accompanying drawings.
FIG. 1. shows the gate arm in operation. The gate arm as shown comprises a stiffening core 1, and a polycarbonate sleeve. A gear motor, 3, is used to move the arm.
FIG. 2. shows a cross section of the arm consisting the core, 1, and the sleeve, 2.
FIG. 3 is a detailed representation of the sleeve showing the co-extruded color strip.